Ecological risk assessment of pesticides in urban streams of the Brazilian Amazon.

The use of pesticides in households and peri-urban areas of the Amazon has increased notably during the last years. Yet, the presence of these contaminants in Amazonian freshwater ecosystems remains unexplored. Here, we assessed the exposure to 18 pesticides and 5 transformation products in the Amazon River and in the urban streams of Manaus, Santarém, Macapá, and Belém (Brazil). Pesticide concentrations were analyzed by liquid and gas chromatography methods. Ecological risks were assessed following a two-tiered approach. First, hazard quotients and an overall hazard index were calculated using toxicity data for standard test species of primary producers, invertebrates, and fish. Second, the pesticides showing moderate-to-high ecological risks in the first tier were evaluated using Species Sensitivity Distributions (SSDs). Our study shows that pesticides are widespread in urban and peri-urban areas of the Brazilian Amazon. The frequency of detection was higher in urban streams than in the Amazon River, with some samples taken in Manaus, Santarém, and Belém containing up to 8 compounds. Most pesticides were measured at relatively low concentrations (ng L-1), except for malathion, carbendazim and the bulk concentration of chlorpyrifos, which were monitored at concentrations above 100 ng L-1. Based on the first-tier assessment, we found moderate-to-high risks for freshwater invertebrates for malathion, chlorpyrifos, and chlorpyrifos-methyl, and moderate risks for malathion to fish. The risk assessment performed with SSDs indicated high risks of malathion and chlorpyrifos-methyl in urban areas, with up to 15% and 5% of invertebrate species potentially affected, respectively. The bulk concentrations of chlorpyrifos resulted in high risks in some urban areas (14-22% of species affected) and in areas of the main river (32-44%) impacted by agriculture. We conclude that pesticide residues may contribute to a biodiversity impact in the Amazon and should be further monitored in urban and peri-urban areas, particularly after heavy rainfall events.

Pharmaceuticals and other urban contaminants threaten Amazonian freshwater ecosystems.

Urban areas in the Brazilian Amazon have grown at an unprecedented rate during the last years. About 90% of the wastewater produced by these urban areas are discharged untreated into Amazonian freshwater ecosystems, constituting a potential environmental pathway for pharmaceuticals and other chemicals consumed by modern societies (e.g. psychostimulants, personal-care products, hormones). The distribution of these chemicals into the Amazon River and their potential risks for freshwater biodiversity have not been evaluated so far. Here, we show the results of the largest chemical monitoring campaign conducted in the Amazon region. We assessed exposure patterns for 43 pharmaceuticals and other urban contaminants in 40 sampling sites distributed along the Amazon River, three major tributaries (Negro, Tapajós and Tocantins Rivers), and four large cities of the Brazilian Amazon (Manaus, Santarém, Macapá, Belém). We assessed risks for freshwater biodiversity using species sensitivity distributions and mixture toxicity approaches. We found that urban areas constitute important hot-spots for chemical contamination, with mixtures containing up to 40 different compounds and exposure concentrations reaching the world's maxima for some of them. We show that chemical pollution can result in long-term effects for up to 50-80% of aquatic species next to urban areas. Moreover, we identified several ubiquitous compounds which can be used as tracers of anthropogenic pressure in the Amazon basin. We conclude that the chemical burden created by urbanization significantly contributes to a biodiversity loss in the region and should be further controlled.

Uma proposta de avaliação integrada de risco do uso de agrotóxicos no estado do Amazonas, Brasil / A proposal for integrated risk assessment of pesticide use in Amazon State, Brasil

Durante os últimos 30 anos, o aumento da população humana no Amazonas introduziu a necessidade de produção adicional de alimentos e levou o governo do estado a desenvolver programas para aumentar e melhorar a produção agrícola. A produção de hortaliças não tradicionais apresentou vários problemas desconhecidos para os agricultores da região, uma vez que estas culturas não são bem adaptadas às condições locais. A suscetibilidade a insetos, fungos e outras pragas, e a competição com vegetação nativa vem forçando os agricultores a usar intensivamente os agrotóxicos. Os agricultores não estavam preparados para o uso adequado desta tecnologia ignorando os riscos dos agrotóxicos para saúde humana e o ambiente. Os agricultores não usam equipamento de proteção individual, porque é caro, desconfortável e inadequado para o clima quente da região. A falta treinamento e o escasso conhecimento sobre os perigos dos agrotóxicos contribuem para a manipulação incorreta durante a preparação, aplicação e disposição das embalagens vazias. Nestas condições, a exposição dos agricultores, suas famílias, consumidores e ambiente é alta. Como um primeiro passo para o entendimento deste problema e a proposição de soluções é proposta a realização de uma avaliação integrada de risco. As três fases do processo, formulação de problema, avaliação da exposição, e caracterização de risco são detalhadas. Programas de educação, treinamento e informação fazem parte das estratégias para a redução do risco do uso de agrotóxicos permitindo o desenvolvimento de uma agricultura ambientalmente sustentável.

During the last 30 years, the increase of the human population in the Amazon introduced the need for additional food production and caused the state government to implement programs to increase and improve agricultural production. The production of nontraditional crops introduced several problems unknown to traditional farmers, since they are not well adapted to tropical conditions. Their susceptibility to insects, fungi and other plagues, and the competition with native vegetation forced farmers to use pesticides intensively. Amazonian farmers were not adequately prepared for the use of this new technology and they ignored the risk of pesticides to human health and the environment. Farmers do not use protective clothing or equipment because they are expensive and not suitable for a tropical climate in which they prove to be very uncomfortable. The lack in training and poor knowledge of pesticide hazards contribute to careless handling during preparation, application and disposal of empty packages. Under such circumstances, exposure of farmers, their families, consumers and the environment is high. As a first step to solve this problem, an integrated risk assessment is proposed. The three stages of the process, problem formulation, exposure assessment, and risk characterization are explained. Training and information programs are part of the strategies risk-reduction in order to build up environmentally sustainable agriculture.

Use and fate of pesticides in the Amazon State, Brazil: risk to human health and the environment.

During the last 30 years, the increase of the human population in the Amazon introduced the need for additional food production and caused the state government to implement programs to increase and improve agricultural production. The production of nontraditional crops introduced several problems unknown to traditional farmers, since they are not well adapted to tropical conditions. Their susceptibility to insects, fungi and other plagues, and the competition with native vegetation forced farmers to use pesticides intensively. Amazonian farmers were not adequately prepared for the use of this new technology; they ignored the risk of pesticides to human health and the environment. Using the region of the state capital Manaus as an example, the characteristics of the pesticide use are described (e.g. the increased use and the lack of personal protective equipment, as well as the legal situation). In detail, the registration status of pesticides used in the State of Amazonas and the state of their registration in the European Union is compared. Finally, it is concluded that the use and the fate of pesticides in the Amazon region has to be monitored. Data of the effects on humans and on the environment have to be collected from the literature or have to be produced in standardized tests, so that an environmental risk assessment becomes possible. Training and information programs are urgently needed in order to build up environmentally sustainable agriculture. Finally, the enforcement of Brazilian laws concerning pesticide registration has to be improved.